84 SUMMAEY OF CUHRENT KESEARCHES RELATING TO 



Porifera. 



Sponges of Chilka Lake.* — -Nelson Annaudale reports on the 

 sponges from this large lagoon on the east coast of Peninsular India. 

 It is connected with the Bay of Bengal. Its area is about 350 square 

 miles ; its depth rarely exceeds two fathoms. Seven sponges occur, 

 fresh-water and marine forms growing together in an intimate manner. 

 The Ust includes Spongilhi alba Carter, Sp. nana sp. n., CUona vasiifica 

 Hancock, Suherifes serireus Thiele, Laxosuberitas aquse-duJcioris Annan- 

 dale, L. lacustris sp. n., and Tetilla ilactyJoidea (Carter) var. lingua nov. 

 Remarkable variations are exhibited by most of the species, and these 

 can be definitely correlated with differences in environment. It is 

 evident that all the species are able to withstand, by one means or 

 another, great changes of sahnity. In Laxosuben'tes lacustris the simple 

 gemmules which are characteristic of the Suberitidse have been replaced 

 by aggregates of gemmules. They are piled together, one on the top 

 of another in several layers, and are held in this position by ^ ertical 

 spicules w^hich transfix them. Lichenoid coherent masses of gemmules, 

 which can be detached as a whole, are thus formed, instead of a single 

 adherent layer as in L. aquse dulcioris. Masses separate off when the 

 sponge dries in hot weather and may float away to other less exposed 

 places. The skeleton of Spongilla alba is strikingly modified to with- 

 stand the violence of the waves in exposed positions in the lake. 



Protozoa. 



Cyst of Amoeba proteus.t— Lucy Agnes Carter describes a cyst of 

 this species. The only previously recorded observations on the encyst- 

 ment of Amaba proteus are those of Scheel in 189".). The cyst is 

 spherical and free, covered with deti'itus and two membranes. It is 

 from lb jx to 140 /a in diameter in life, shrinking to from GO /a to 110 /a 

 after preservation. A combined study of the process of encystment, as 

 seen in life and in the sectional cysts, leads to the conclusion that after 

 the cementing of the debris the amoeba-body withdraws itself from its 

 protective envelope, and, ronnding itself off, forms its outer membranous 

 wall. After this a slight contraction of the protoplasm as it concentrates, 

 and the formation of the second membranous wall, completes the 

 protection of the now encysted amoeba. As the cyst ripens, the mem- 

 branous walls contract and crumple ; the wall of debris remains intact 

 till the young amoebae are ready to escape. The period of encystation 

 lasts from ten to twelve weeks. 



Inside the cyst the nucleus breaks down, the chromatin and plastin 

 are distributed throughout the cytoplasm, secondary nuclei are formed. 

 These are of the protokaryon type, showing a relatively large karyosome 

 slung up in the nuclear sap by achromatin radiating fibres, each ter- 

 minating in a chromatin granule similar in all appearance to the 

 karyosome, but retaining the stain less intensely. The nuclei then cut 



* Mem. Indian Museum, v. (1915) pp. 23-54 (3 pis.). 



t Proc. E. Phys. Soc. Edinburgh, xix. (1915) pp. 204-12 (1 pi.). 



